Fire Safety Science Digital Archive

The most effective fire extinguishing agents for pool fires are Aqueous Film Forming Foams (AFFF). Today, all available AFFF contain polyfluorinated compounds (PFC), i.e. polyfluorinated tensides (PFT), to establish the aqueous film on the surface of a burning liquid. These fluorinated compounds are persistent, potentially bio-accumulative and toxic. Therefore it is essential to find environmentally sound substitutes for these problematic surfactants. Commercially available fluorine-free foams (FfreeF) lack the ability of aqueous film formation. Although FfreeF are performing well in many situations [1,2], there are numerous scenarios where an aqueous film forming component is mandatory for fast fire extinguishing, e.g. in case of burning liquids. To achieve a well performing AFFF, a new approach is to replace the film forming PFC/PFT by siloxane surfactants. Today, siloxane surfactants are typically used in plant protective agents, in textile surface treatment and as lubricants. As the properties of commercially available siloxane surfactants are not suitable for AFFF, new siloxane surfactants were designed, synthesized and tested for their suitability as film forming ingredients in AFFF formulations. The surface activity and foaming behaviour of model formulations have been determined. Finally, one experimentally fluorine-free AFFF formulation has been subjected to fire tests. In this context a new fire test for scarcely available chemicals is presented.